code: def test_interpolate_linear(
      input_dtype: PolarsDataType, output_dtype: PolarsDataType
  ) -> None:
      df = pl.LazyFrame(
          {"a": [1, None, 2, None, 3]}, schema={"a": input_dtype}
      )
      result = df.with_columns(pl.all().interpolate(method="linear"))
      assert result.schema["a"] == output_dtype
      expected = pl.DataFrame(
          {"a": [1.0, 1.5, 2.0, 2.5, 3.0]}, schema={"a": output_dtype}
      )
      assert_frame_equal(result.collect(), expected)
  
file_path: polars/py-polars/tests/unit/operations/test_interpolate.py
imports: from __future__ import annotations
  from datetime import date, datetime, time, timedelta
  from typing import TYPE_CHECKING, Any
  import pytest
  import polars
  from polars.testing import assert_frame_equal
label_desc: Use image node_id 1 for calling a global function with example usage: test_interpolate_linear(input_dtype, output_dtype) without return types